A conventional mixer circuit proposed in an article by N. Zhang et al., entitled “W-Band Active Down-Conversion Mixer in Bulk CMOS,” in IEEE Microwave and Wireless Components Letters, vol. 19, no. 2, pp. 98-100, February 2009, operates in a 76 GHz-77 GHz frequency band, and achieves low power consumption. However, its conversion gain is only −8 dB, and its LO-RF isolation and LO-IF isolation are both low, where LO, RF and IF respectively denote a local oscillator signal input terminal, a radio frequency signal input terminal and an intermediate frequency signal output terminal.
Another conventional mixer circuit proposed in an article by J. Kim et al., entitled “W-band double-balanced down-conversion mixer with Marchand baluns in silicon-germanium technology,” in Electronics Letters, vol. 45, no. 16, pp. 841-843, July 2009, operates in a 75 GHz-110 GHz frequency band, and has a conversion gain of 14.4 dB. However, its power consumption is high, and its LO-RF isolation is low.
Measurement results of the above-mentioned conventional mixer circuits are shown in Table 1. It is known from Table 1 that each conventional mixer circuit is unable to simultaneously achieve low power consumption and high conversion gain.
TABLE 1N. ZhangJ. KimConversion Gain (dB)−814.4LO-RF Isolation (dB)2130  LO-IF Isolation (dB)32—RF-IF Isolation (dB)——Power Consumption (mW) 692.4FOM (figure of merit)1.01 × 10−40.178 × 10−4